vitamin D

Whether dietary supplementation with vitamin D is beneficial, in terms of preventing disease, has been controversial. However, vitamin D has been reported to increaseÂ immune cellsâ€™ production of microbe-fighting proteins. That’s why Emory doctorsÂ have been testing whether high doses of vitamin D couldÂ be helpful for critical care patients, who need to ward off infections.

The results of a small-scale clinical trial, presented in Denver this week at the American Thoracic Society meeting, suggest thatÂ high doses of vitamin D could decrease the length of hospital stays in critically ill patients with respiratory failure. Read more

In people with HIV, low vitamin D levels have been linked to thicker carotid arteries as well as a weaker comeback for the immune system after starting antiretroviral therapy.

These results, published online recently in the journal Antiviral Therapy, are the first to confirm an association between low vitamin D levels and a measure of higher cardiovascular risk in people with HIV. They also suggest that the benefits of vitamin D supplementation for people with HIV should be evaluated in a clinical trial.

Allison Ross, MD, is an infectious disease specialist in the Department of Pediatrics and theÂ Emory-Children's Pediatric Research Center.

The advent of effective antiretroviral therapy against HIV has dramatically improved life expectancies for people with HIV over the last 15 years. The presence of HIV is known to perturb cardiovascular health, even in the absence of an active infection. Since vitamin D levels are known to have an impact on the immune system and cardiovascular disease risk, that drove infectious disease specialist Allison Ross and her colleagues to probe these connections in people living with HIV.Â The results were also described on the Web sitesÂ AidsMeds and NAM/AidsMap.

Ross studied a group of HIV-positive people enrolled in Case Western Reserve Universityâ€™s HIV clinic in Cleveland. Colleagues from Emory and Case Western were co-authors.

They tested vitamin D levels, immune function and heart health in 149 HIV-positive people and a matched group of 34 HIV-negative people. Vitamin D levels were significantly lower in the HIV-positive group, even when controlling for known factors that affect vitamin D.

The researchers looked at how much the immune system was able to come back after starting retroviral therapy. This involves comparing someoneâ€™s lowest ever CD4 T cell count from the current CD4 count. They found that people with the poorest level of immune restoration were the most likely to have the lowest level of vitamin D. In addition, people with the lowest vitamin D levels were more than 10 times as likely to have thickening of the carotid arteries, as measured by ultrasound.

Inflammation can be a driving factor for heart disease, but in the study, low vitamin D was not linked to higher levels of inflammation markers.Â Additional research could determine whether those who are starting antiretroviral therapy would see better immune recovery if they took a vitamin D supplement.

Vitamin D may be called a vitamin, but itâ€™s not. Thatâ€™s because we can make it by exposing our skin to sunshine. So, technically that makes vitamin D a hormone–a steroid hormone to be exact. In fact, we get most of our exposure to vitamin D directly from sunshine and some from foods such as milk, fortified orange juice and oily fishes like salmon.

But no matter what you call it or where you get it, vitamin D is vital to growth, development and maintenance of our cells. Doctors have known for decades that vitamin D promotes calcium uptake and bone formation, but evidence is accumulating that it regulates the immune system and the development of the nervous system. Growing evidence suggests a link between low vitamin D levels and Parkinson’s disease, but whether this is a cause-and-effect relationship is unknown.

Marian Evatt, MD

Thatâ€™s why Emory neurologist Marian Evatt, MD, and her colleagues are conducting a clinical trial exploring the effects of vitamin D supplementation on patients with Parkinson’s disease who have low vitamin D levels. The study also includes further epidemiological studies of vitamin D in Parkinson’s disease.

Parkinson’s disease affects nerve cells in several parts of the brain, particularly those that use the chemical messenger dopamine to control movement. The most common symptoms of Parkinsonâ€™s disease are tremor, stiffness and slowness of movement.

â€œVitamin D has become associated with many chronic diseases: diabetes, hypertension, cardiovascular disease, and some of the autoimmune diseases, including multiple sclerosis,â€ says Evatt. â€œBut we havenâ€™t yet determined the specific effect of vitamin D in specific conditions because it has such broad effects.â€

To hear Evatt talk about what vitamin D is, what it does, and why we need it, please go to Emory’s latest Sound Science podcast.